## 1 Introduction  
Internet of Things (IoT) became a major instrument that can significantly help modern cities to achieve their sustainable development goals [1; 2; 3]. Today, the IoT approach became a significant basis of the smart city [2] The active development of the IoT for cities goes alongside many other changes in the city itself. Modern cities have focused on such approaches as green architecture, new ways of planning, humancentric inclusive streets, energy efficiency, and many others [4; 5; 6; 7]. Many of those approaches' biotechnologies are also becoming an influencer on the view of our future [8], including the view of the city [9]. The term \"biotechnology\" covers a number of different approaches in the many fields of application including medicine, pharmacy, agriculture, and environmental technologies, among others. Here, only a very small part of those approaches will be discussed. The main focus will be done on the application of living organisms for different city needs as a part of green infrastructure. This small part of many biotechnological approaches already today can give the possibility to produce food and treat air and water in the city, thus sufficiently influence the city's sustainable development. Both city biotechnology and city IoT develop almost in parallel at the same time and the necessity to provide research in the field of integration for those technological approaches is arising [1; 8; 10]. The most actively discussed biotechnological approaches for new production in the city are as follows:  
* Higher plants as a major air treatment biosystem of cities: today there are several technologies such as rain gardens and green streets where higher plants also provide rainwater treatment [11; 12];
* Urban vertical farming systems as a novel food-producing paradigm [13]: it is necessary to mention that such technology not only actively uses a high level of automation and robotization but has also become an effective carbon dioxide consumer that positively influences the city environment;
* Photobioreactors for microalgae production that can be a part of the architecture or for home air treatment [14; 15]: phototrophic microorganisms have a higher rate of carbon dioxide fixation and can be the source of multiple useful substances that can be applied from biofuel and the production of biopolymers to fertilizers, food, and even the pharmacy industry [16]; additionally, it has been shown that phototrophic microorganisms can participate in rain and thaw water treatment [17], so photobioreactors can be part of a city's water system. These technologies require additional operations to include them into a city's IoT. Their applications lead to new data generations and new control systems that operate with additional sensors that are needed to be added to the wireless sensor networks (WSNs) [10]. However, several recent advancements in the biotechnology can give rise to additional opportunities that enhance IoT capabilities in some fields. Some of those approaches are as follows:  
* Energy harvesting technologies based on microbial fuel cells (MFCs) that are able to provide a power supply for IoT wireless sensors [18] that can operate consuming organic compounds from different wastewaters [19];
* Novel sensors for environmental monitoring based on biological sensing that can enhance chemical and biological sensing for IoT [10; 20];
* New actuating systems with living cells integration [21] based on the synthetic biology approaches that give rise to the ability to develop a novel interface with biotechnological systems in the city [22]. Figure 1 illustrates these biotechnologies and their interactions with a city's IoT. Figure 1: Interactions between several biotechnologies and a city’s Internet of Things (IoT). Thus, in this paper, the integration of both biotechnology groups in the IoT will be discussed with a focus on the new possibilities and issues that will arise for a city's IoT.